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Unique QA/QC Requirements for Analytical Chemistry at LANL

Lav Tandon, NMT-1 Margaret A. Gautier, NMT-1 Crail F. Hammond, NMT-1 Donivan R. Porterfield, NMT-1

American Nuclear Society 1998 Winter Meeting in Washington, DC and ANS Trasnactions

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Unique QNQC Requirements for Analytical Chemistry at LANL

L. Tandon, M. A. Gautier, C. F. Hammond, and D. R. Porterfield,

NMT-1 CMR Los Alamos National Laboratory, MS K-484, Los Alamos, NM 87545, USA

One of the missions of group NMT-1 (Nuclear Materials Technology

Divisiodhalytical Chemistry) at Los Alamos National Laboratory (LANL) is to provide

analysis of both radioactive and nonradioactive materials to address the stockpile

stewardship needs of the US Department of Energy (DOE). Trace to high levels of

various constituents are measured using traditional analytical methods and state-of-the-art

instrumental methods. Our capabilities include Pu and U assay, wet chemistry, plasma

spectroscopy, mass spectrometry radiochemistry, x-ray fluorescence, anion and cation

analysis, special standards preparation, surface analysis, and gas analysis.

We are currently developing and implementing a plan to independently assess the

quality of the analytical data produced by NMT-1. Nuclear materials of a matrix similar

to the client’s samples but having different concentration levels of analytes that are

representative of the client’s samples will be used.’ Well-characterized, stable,

homogeneous materials have been identified as possible candidates for single-blind

quality control (QC) samples. These materials include Pu metal, Pu oxide, uranium

metal, uranium oxide, and uranium-plutonium mixed oxide with varying degrees of

purity. These single-blind samples will be periodically distributed along with regular

client samples to be analyzed by the above mentioned analytical methods. Certified

reference materials (CRMs) would be an ideal choice for QC samples because they

provide traceability to a national measurement base. However, there is only one matrix-

matched CRM (uranium oxide powder) available in the US that has been characterized

for metal impurities. We plan to use this CRM frequently. The QC materials to be

discussed in the presentation are the various oxide powder blends, including Pu oxide, U

oxide, and U-Pu oxide (MOX), all of which were previously prepared at LANL for

analysis of metallic and nonmetallic impurities. These QC materials are discrete batches

for which previous random sampling and analysis have verified homogeneity. Special

sampling and packaging instructions were followed to ensure safety and minimize

contamination, loss of volatile elements, and deterioration of the sample. The control

limits assigned to an analyte include analytical uncertainty computed in many cases from

previous interlaboratory exchange programs, the propagated error of blending

preparation, and the uncertainty of the components in the matrix material.2 The overall

administration of the program is handled by the Quality Assurance (QA) team in our

group and will include continuous surveillance of the laboratory operations, the large task

of recording all the results obtained from the analysis of these QC samples, and frequent

review using control charts and statistical tests of the reported QC data. The statistical

review of the data is designed to independently monitor not only the accuracy and

precision of the results but also provide information on bias trends and identify potential

problems related to training of personnel, analytical methodology, and defective

instrumentation.

An interlaboratory performance evaluation program for nuclear materials is also

currently being set up at LANL. Various aspects of this program to be discussed include

(1) a summary of the chemical specification for the source materials, (2) a discussion of

the preparation, characterization, packaging, and record keeping of the materials, and (3)

administration of the program, including the tabulation and preparation of control charts

of samples to analyze problems unique to one laboratory or common to all participating

laboratories.’ This performance evaluation program will also validate the effectiveness of

internal QC and serve as a means of evaluating analytical performance by the various

participating laboratories. Even though these extensive QC programs will incur cost in

terms of time, effort, and resources, we anticipate that this cost will be offset by increased

confidence in our analytical results in support of the DOE stockpile stewardship program.

1. D. A. BECKER, Primary Standards in Activation Analysis, J Radioanal. N u l .

2. J. E. REIN, R. K. ZEIGLER, G. R. WATERBURY, W. E. McCLUNG, P. R. Quality Assurance Program for Surveillance of

Chem., 113 (l), 5, 1987.

PRAETORIUS, W. L. DELVIN, Fast Reactor Mixed Oxide Fuel Analytical Chemistry, UEA-SR-7/1, 149,1976.